US Comand
The US COMAND being referred to is a Head Unit (HU) and would not (automatically) provide you with an AUX input. The AUX jack is located in the glove box and, unless you already have it, you'd have to do a retrofit.
Unless you're looking to add NAV to your w211 (which would also require the DVD NAV unit in your trunk), I'm not so sure that upgrading to the US COMAND would provide you with much more than you already have (and at a significant cost).
Steve (MBenzNL), however, is the man with the answers and would be able to give you more [acurate] information on this topic. Contact him for any questions regarding your upgrade options.
GL.


